I selected a piece of board 20x50cm for this painting, not too big and not too small, the ratio feels 'right' for the sense of space that I want to portray. (There is no reason in particular for this size it just feels instinctively right and is proportionate to some of the preparation sketches that I had done.)
I began the under painting on a warm neutral ground and very loosely blocked in the main shapes of sky, sea and sand. The second stage in this painting was about setting my darkest tone in. I did this early on using ivory black in the dark masses of the water. I knew I wouldn't end up seeing the black after the layers of blue were painted on top but they would quickly give the depth of the shadow that I wanted in this area.
Now the darks were in place I could easily judge how light the lights needed to be. More often I paint the other way around and put my lighter ranges in first but the painting was willing me to work in reverse. I thought I would go with it and let the painting dictate the way it wanted to be painted.
By the end of stage 3 you can see pretty much all of the black has been painted over. (As a side note ivory black mixed with buff titanium is a very useful colour for sand shadow in evening light. - you can see my old fear of tube black has pretty much disappeared over the last year. ;o) ) As usual I have used a number of blues; coeruleum, cobalt, ultramarine (a blue that I very rarely use) and indigo.